- Chemoselective transfer hydrogenation of nitriles to secondary amines with nickel(II) catalysts
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Herein we report the selective transfer hydrogenation (TH) of nitriles to secondary (2°) amines with simple Ni(II)-catalysts using ammonia borane (AB) as a source of hydrogen (H2). A bis(pyrazolylmethyl)pyridine (L1) or ethylenediamine (L4) ligated Ni(II) pre-catalyst, created in situ, could hydrogenate several aromatic- and aliphatic nitriles in full conversions and isolated yields of up to 88% under ambient temperature and in very short reaction times. Deuterium labelling experiments illustrated the incorporation of a proton on the nitrogen and hydride on the α-carbon of dibenzylamine. Using α-picoline borane, containing no dissociable protons, assisted with the postulation of a two-step TH mechanism of benzonitrile. AB was subjected to dehydrogenation and it was observed that a maximum of 2.96 equivalents of H2 gas could be generated from NiCl2?6H2O/L1.
- Vermaak, Vincent,Vosloo, Hermanus C.M.,Swarts, Andrew J.
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- Phosphine-Free Manganese Catalyst Enables Selective Transfer Hydrogenation of Nitriles to Primary and Secondary Amines Using Ammonia-Borane
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Herein we report the synthesis of primary and secondary amines by nitrile hydrogenation, employing a borrowing hydrogenation strategy. A class of phosphine-free manganese(I) complexes bearing sulfur side arms catalyzed the reaction under mild reaction conditions, where ammonia-borane is used as the source of hydrogen. The synthetic protocol is chemodivergent, as the final product is either primary or secondary amine, which can be controlled by changing the catalyst structure and the polarity of the reaction medium. The significant advantage of this method is that the protocol operates without externally added base or other additives as well as obviates the use of high-pressure dihydrogen gas required for other nitrile hydrogenation reactions. Utilizing this method, a wide variety of primary and symmetric and asymmetric secondary amines were synthesized in high yields. A mechanistic study involving kinetic experiments and high-level DFT computations revealed that both outer-sphere dehydrogenation and inner-sphere hydrogenation were predominantly operative in the catalytic cycle.
- Sarkar, Koushik,Das, Kuhali,Kundu, Abhishek,Adhikari, Debashis,Maji, Biplab
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p. 2786 - 2794
(2021/03/03)
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- Selective Synthesis of Secondary Amines from Nitriles by a User-Friendly Cobalt Catalyst
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Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3?BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH?BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities. (Figure presented.).
- Sharma, Dipesh M.,Punji, Benudhar
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supporting information
p. 3930 - 3936
(2019/07/12)
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- 1,3,4-OXADIAZOLE SULFONAMIDE DERIVATIVE COMPOUNDS AS HISTONE DEACETYLASE 6 INHIBITOR, AND THE PHARMACEUTICAL COMPOSITION COMPRISING THE SAME
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The present invention relates to novel compounds represented by the formula I having histone deacetylase 6 (HDAC6) inhibitory activity, stereoisomers thereof or pharmaceutically acceptable salts thereof, the use thereof for the preparation of therapeutic medicaments, pharmaceutical compositions containing the same, a method for treating diseases using the composition, and methods for preparing the novel compounds. (I) The novel compounds, stereoisomers thereof or pharmaceutically acceptable salts thereof according to the present invention have histone deacetylase (HDAC) inhibitory activity and are effective for the prevention or treatment of HDAC6-mediated diseases.
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Paragraph 701; 702; 703
(2017/02/24)
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- Mild and Selective Cobalt-Catalyzed Chemodivergent Transfer Hydrogenation of Nitriles
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Herein, we describe a selective cobalt-catalyzed chemodivergent transfer hydrogenation of nitriles to synthesize primary, secondary, and tertiary amines. The solvent effect plays a key role for the selectivity control. The general applicability of this procedure was highlighted by the synthesis of more than 70 amine products bearing various functional groups in high chemoselectivity. Moreover, this mild system achieved >2000 TONs (turnover numbers) for the transfer hydrogenation of nitriles.
- Shao, Zhihui,Fu, Shaomin,Wei, Mufeng,Zhou, Shaolin,Liu, Qiang
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supporting information
p. 14653 - 14657
(2016/11/23)
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- Synthesis of a novel secondary dialkylammonium salt with three stations and its threading through the cavity of two crown ethers
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In this paper, a novel secondary dialkylammonium salt with three stations (G1) was synthesized in 5 steps. 1H NMR was used to study the threading of G1 through the cavity of dibenzo-24-crown-8 (DB24C8) and benzo-21-crown-7
- Shen, Jianfen,Luo, Yan,Chen, Rener,Han, Deman,Jiang, Huajiang,Zhou, Qizhong
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p. 100 - 104
(2013/07/26)
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- Combining different hydrogen-bonding motifs to self-assemble interwoven superstructures
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A series of carboxyl-substituted dibenzylammonium salts have been cocrystallized with the macrocyclic polyethers dibenzo[24]crown-8 (DB24C8) and bis-p-phenylene[34]crown-10 (BPP34C10) to effect the noncovalent syntheses of a wide range of interwoven superstructures in the solid state. In all cases, the dibenzylammonium cations thread through the cavities of the macrocyclic polyethers - primarily as a result of N+-H ··· O hydrogen bonds, with occasional secondary stabilization from C - H ··· O and aryl-aryl interactions - to form pseudorotaxane complexes possessing supplementary recognition sites (specifically, carboxyl groups) for further intercomplex association through hydrogen bonding. One unit of each of the dibenzylammonium cations threads through the DB24C8 macrocycle to make single-stranded, carboxyl-containing [2]pseudorotaxanes that interact further with one another to produce novel supramolecular architectures as a result of hydrogen bonding between their carboxyl groups (the carboxyl dimer supramolecular synthon), or between carboxyl groups and polyether oxygen atoms. Elaborate architectures, such as side-/main-chain pseudopolyrotaxanes and a daisy-chain-like supramolecular array, were thus synthesized noncovalently. BPP34C10 can accommodate two cations within its macrocyclic interior to form carboxyl-containing [3]pseudorotaxanes in which BPP34C10 acts as a girdle that helps to control the spatial orientation of the carboxylic acid-containing recognition sites for additional intersupramolecular association through the carboxyl dimer. PF6/- anions were also found to play a role in the self-assembly processes. When the anions interact with the [3]pseudorotaxanes, these recognition sites are oriented in the same direction. This leads to the formation of doubly-encircled multicomponent supermolecules when BPP34C10 is cocrystallized with dibenzylammonium cations bearing only one carboxyl substituent. On the other hand, when BPP34C10 is cocrystallized with an isophthalic acid-substituted ammonium cation, there is no evidence of any anion assistance to self-assembly; the isophthalic acid units are aligned in opposite directions, creating an interwoven supramolecular cross-linked polymer.
- Ashton, Peter R.,Fyfe, Matthew C. T.,Hickingbottom, Sarah K.,Menzer, Stephan,Stoddart, J. Fraser,White, Andrew J. P.,Williams, David J.
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p. 577 - 589
(2007/10/03)
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- Self-Assembling - and Rotaxanes from Secondary Dialkylammonium Salts and Crown Ethers
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The self-assembly of three new rotaxanes - two rotaxanes and a rotaxane - formed by a "threading followed by stoppering" approach is described.These template-directed syntheses rely on the formation of pseudorotaxane intermediates, which self-assemble in solution from functionalized secondary dialkylammonium hexafluorophosphate threads and macrocyclic polyether rings (either dibenzocrown-8 or its asymmetric constitutional isomer).The stoppers - substituted 1,2,3-triazoles - were created by thermally allowed 1,3-dipolar cycloaddition between azido groups, which terminate the threads, and di-tert-butyl acetylenedicarboxylate. - Keywords: interlocking molecules; molecular recognition; pseudorotaxanes; rotaxanes; template syntheses
- Ashton, Peter R.,Glink, Peter T.,Stoddart, J. Fraser,Tasker, Peter A.,White, Andrew J. P.,Williams, David J.
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p. 729 - 736
(2007/10/03)
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- Substituted 1,4-diamino-2-butene stabilizers
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N,N,N',N'-Tetrasubstituted 1,4-diamino-2-butenes where the substituents are alkyl, cycloalkyl, aralkyl, aryl or mixtures thereof provide effective antioxidant protection to lubricants and/or synthetic polymers.
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- N,N'-alkenylene amine/mercaptotolyl-imidazole blends as high temperature antioxidants for elastomers
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Elastomers are very effectively stabilized against thermal and oxidative degradation at elevated temperatures with a blend of an N,N,N',N'-tetrasubstituted 1,4-diamino-2-butene, where the substituents are alkyl, cycloalkyl, aralkyl, aryl or mixtures there
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